How long can tartar stay on your teeth before it becomes a problem?

I have very visible tartar on my back tooth. It has been there for about a month. It has been bothering me for a while and my gums have been bleeding a lot while brushing. It looks like my gum is actually starting to recede a little bit too. I have a dentist appointment for a cleaning in 2 weeks time. Can I wait this long to get the tartar removed or will it cause permanent damage?